1. Field of the Invention
The present invention is related to a body structure of a forklift truck applied mainly to a forklift truck driven by an internal combustion engine, the body comprising a pair of left and right side frames extending in the longitudinal direction of the body and a cross member of which both lateral side ends are fixed to said side frames on the inside faces thereof and which is located above an rear axle of the forklift truck.
2. Description of the Related Art
A forklift truck is provided with a counter weight in the rear of the forklift truck to balance the weight of a load carried on the forklift provided in the front thereof, so force due to the weight of the counter weight and counter force from the rear axle due to traveling of the vehicle act on the rear part of the body frame. In a conventional forklift truck, two vertical cross member plates are fixed to a pair of side members to cope with such forces as shown in FIG. 6. In the drawing, reference numeral 106 is a body frame, 107 are a pair of left and right side frames extending in the longitudinal direction of the body frame, 020 is a cross member consisting of two vertical plates fixed to the inside faces 107a of the side frames 107, and 108 are erect members provided at the rear end of each of the side frames.
Said cross member 020 consists of two vertical plates 20 disposed parallel to each other with a certain distance and an axle supporting member 22 welded to the vertical plates 20 at the lower end thereof, a rear axle not shown in FIG. 6 being located under the axle supporting member 22. Both lateral side ends of each of the vertical plates 20 are welded to the inside faces 107a of the side frames 107.
In Japanese Laid-Open Patent Application No. 2001-48497 is disclosed a forklift truck which is composed such that a front frame having a pair of left and right outer rails and a rear frame having a pair of left and right inner rails are provided and the inner rails are received in the outer rails so that the inner rails can be slid relative to the outer rails without interfering with front and rear wheels in order to change the wheel base of the forklift truck.
In a forklift truck provided with a counter weight (not shown in FIG. 6) to balance the weight of a load carried on the fork provided in the front of the vehicle, force F2 in the longitudinal direction of the truck body resulted by the moment around the supporting point of the counter weight due to the offset of the center of gravity of the counter weight from the bearing point of the counter weight on the body frame acts on the cross member 020 in addition to force F1 in vertical direction acting on the axle support member 22 from the rear axle resulting due to the vertical shock which occurs when the forklift truck is traveling, as shown in FIG. 6. Therefore, each force F1 and F2 acts to bend the cross member 020 and the welded parts of the both lateral ends of the vertical plates 20 of the cross member 020 and left and right side members 107 are considerably stressed by the bending moment due to force F1 and F2.
In the prior art of construction as shown in FIG. 6, as the cross member 020 to which vertical force F1 and lateral force F2 are applied at the lateral center portion thereof is composed such that two vertical plates 20, to which an axle support member 22 is welded at the lower ends of the vertical plates, are disposed in parallel to each other and welded to the inside faces 107a of the side frames 107, the distance 21 between the plates must be determined to be somewhat large in order to secure the strength of structure.
However, with a structure like this, the space 21 between the vertical plates 20 becomes a dead space where parts can not be located, and it is difficult to construct a compact vehicle.
Generally, an engine exhaust muffler (not shown in the drawing) is located at the back of the rear side vertical plates 20 of the cross member 020 parallel to the plate, so the length of the forklift truck becomes inevitably long. Further, as the cross member 020 which is located under the radiator of the engine is provided as mentioned above, the cooling air of the radiator conducted to the exhaust opening formed in the counter weight is liable to flow toward the underside of the body resulting in an easy winding-up of dust on the ground. Therefore, it is needed to provide an additional member in order to prevent the flow of the cooling air toward the underside of the body, which causes a complication in structure and an increase in manufacturing cost.